Battery Choices for Different Plug-in HEV Configurations

Plug-in HEV Forum and Technical Roundtable South Coast Air Quality Management District

Diamond Bar, CA

July 12, 2006

Ahmad Pesaran, Ph.D.National Renewable Energy Laboratory

With support from FreedomCAR and Vehicle Technologies Program

Office of Energy Efficiency and Renewable Energy U.S. Department of Energy

NREL/PR-540-40378

3

NREL’s

Plug-in HEV R&D Activities •

Battery Level—

R&D support to developers—

Testing and evaluation –

Sprinter PHEV testing —

Thermal characterization and design—

Supporting requirement analysis and development•

Vehicle Level—

Real-world PHEV simulations -

fuel economy and recharging

—

Support development of test procedures for PHEVs

and MPG reporting

—

Evaluation of alternative PHEV design strategies»

all-electric vs. blended operation—

PHEV design cost-benefit analysis•

Utility Level—

Assessment of PHEV impacts on utilities—

Exploring synergies between PHEVs

and wind power

—

V2G opportunities for PHEVs

in regulation services•

National Level—

Benefits assessment -

oil use and emissions—

Renewable community –

linking PHEV to renewable •

Analysis support to DOE, OEMs, and others —

Working to identify and overcome barriers to PHEV adoption

Secretary of Energy visiting NREL on 7/7/06 for ribbon cutting of the new S&T

Facility and then discussing plug-in hybrids with EnergyCS

& Hymotion

4

Topics of the Presentation

•

Battery Technologies for PHEVs—

State-of-the-art

—

Advances•

Impact of Vehicle Attributes on Battery

—

EV Range—

System Architecture

—

Driving cycles and profiles•

Concluding Remarks and a Few Thoughts

5

Key Messages

•

There is a broad spectrum of HEV-PHEV designs leading to different battery requirements.

•

Batteries are available that could meet the energy and power demands for PHEVs, but cost and limited cycle/calendar life are major barriers for affordable PHEV introduction.

•

NiMH could do the job•

Li-ion are potentially best candidates•

All Li-ions are not “created equal”•

There are emission benefits with PHEVs, but the difference between pure EV range and blended EV range impacts may need to be understood

•

PHEVs

are the most cost-effective choice in a scenario of projected (low) battery costs and high fuel costs.

6

Batteries in Current PHEVs

Johnson Controls/SAFT

Varta

Valence Technology

Kokam

A123 Systems

Electro Energy Inc.

NiM

HC

o/N

i bas

edLi

-Io

nIr

on

pho

sph

ate

base

d Li

-Io

n

7

High Power Battery and Ultracapacitor Characteristics for Hybrid Vehicles

Parameter VRLA NiMH Li Ion Ultracap

Cell configurationParallel plates; spirally wound

cylindrical

Spirally wound cylindrical; parallel

plates

Spirally wound cylindrical &

elliptic

Spirally wound cylindrical &

elliptic Nominal cell voltage (V) 2 1.2 3.6 1.8 Battery electrolyte Acid Alkaline Organic Organic Specific energy, Wh/kg 25 40 60 to 80 5 Battery/Module specific power, 10 sec, W/kg 23ºC, 50% SOC 400 1300 3000 >3000 -20ºC, 50% SOC 250 250 400 >500 Charge acceptance, 10 sec. W/kg

23ºC, 50% SOC 200 1200 2000 >3000 2010 Projected Cost >100,000 per year $/kWh, Module 100.00 500.00 700.00 20,000.00 $/kWh, Full pack 140 600 1100 25000 $/kW, pack 9.00 18.00 22.00 40.00 Energy efficiency Good Moderate Good Very Good Thermal managements requirements

Moderate High Moderate Light

Electrical control Light Light Tight Tight

Source: M. Anderman, AABC-04 Tutorial, San Francisco, CA June 2004

8

Qualitative Comparison of Large-Format Battery Technologies for PHEVS

Attribute Lead Acid NiMH Li-IonWeight (kg)

Volume (lit)

Capacity/Energy (kWh)

Discharge Power (kW)

Regen

Power (kW)

Cold-Temperature (kWh & kW)

Shallow Cycle Life (number)

Deep Cycle Life (number)

Calendar Life (years)

Cost ($/kW or $/kWh)

Safety-

Abuse Tolerance

Maturity -

Technology

Maturity -

Manufacturing

Key (relative to each other)

PoorFair

Good

9

NiMH has Matured in Power and Energy

Source: Reproduced from A. Fetcenko

(Ovonic

Battery Company) from the 23rd

International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

Panasonic EV

Ovonic

95 Ah EV module used in Toyota RAV 4

Specific energy ranging from 45 Wh/kg to 80 Wh/kg depending on the power capability.

10

NiMH batteries are forecasted to dominate the HEV market for a while

Panasonic

Cobasys

Electro Energy

Pack with bipolar Cells/Modules

6.5 Ah Battery for Toyota

Bipolar pack in a Plug-In Prius

EV module (left) and 42V HEV batteries

Source: C. Pillot

(Avicenne) from the 23rd

International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

Forecast

Sanyo

6.5 Ah HEV cells in Ford Escape HEV

Source: Images provided by James Landi of Electro Energy Inc.

Source: Sanyo website news

11

Li Ion Technology –

Diverse Chemistry & Opportunity

Voltage ~3.2-3.8 VCycle life ~1000-3000Wh/kg >150Wh/l

>400Discharge -30 to 60oCShelf life <10%/year

Source: Robert M. Spotnitz, Battery Design LLC, “Advanced EV and HEV Batteries,”

2005 IEEE Vehicle Power and Propulsion Conference, September 7-9, 2005, IIT, Chicago, IL

Many cathodes are possibleCobalt oxide

Manganese oxideMixed oxides with Nickel

Iron phosphateVanadium oxide based

Many anodes are possibleCarbon/Graphite

Titanate

(Li4

Ti5

O12

)Titanium oxide based

Thin Oxide basedTungsten oxide

Many electrolytes are possibleLiPF6

basedLiBF4

basedVarious solid electrolytes

Polymer electrolytes

12

Characteristics of Cathode Materials

Lower potential can provide greater stability in electrolyteCobalt oxide most widely used in consumer cells but recently too

expensiveLiMn1/3

Co1/3

Ni1/3

O2

newer than LiNiCoO2Mn2

O4

around for many years –

not competitive for consumer –

good for high powerLiFePO4

–

very new –

too low energy density for consumer electronics -

safe on overcharge but need electronics to prevent low voltage-

may require larger number of cells due to lower voltage

Material Δx mAh/g avg V Wh/kg Wh/lLiCoO2 0.55 151 4.00 602 3073LiNi0.8Co0.15Al0.05O2 0.7 195 3.80 742 3784LiMn2O4 0.8 119 4.05 480 2065LiMn1/3Co1/3Ni1/3O2 0.55 153 3.85 588 2912LiFePO4

* 0.95 161 3.40 549 1976*Typically diluted with 10% carbon for electronic conductivity

Theoretical values

for a battery system relative to graphite anode and LiPF6

electrolyte

Source: Robert M. Spotnitz, Battery Design LLC, “Advanced EV and HEV Batteries,”

2005 IEEE Vehicle Power and Propulsion Conference, September 7-9, 2005, IIT, Chicago, IL

13

Nano-materials in Li-Ion Batteries Improve Performance & Life

•

Easier diffusion of Li-ion into and out of the host—

High specific capacity at high rate•

Increased electrode surface area and thus higher rates

•

Stable 3 dimensional host materials •

Small dimensional change as Li-ions are cycled in and out

—

Improved cycling life due to less structural change—

Low irreversible capacity loss •

Exhibit of both faradaic

and non-faradaic

capacity

—

Higher capacity retention•

Enabling new materials

Source: Excepts A. Singhal

(NEI Corporation) and E. House (Altair Nanotechnologies) from the 23rd

International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

14

Many Oxide Based Li-Ion Batteries are Available

•

Johnson Control•

Saft

•

LG Chem•

Kokam

•

Sony•

Sanyo

•

Samsung•

Panasonic

•

Electrovaya•

NEC Lamilion

Energy

•

Nissan•

Lishen

•

Pionics•

SK Corp

•

GS Yuasa•

Altair Nanotechnologies

15

Lithium Iron Phosphate (LiFePO4

) Cathodes

+ High stability and non-toxic+ Good specific capacity+ Flat voltage profile+ Cost effective (less expensive cathode)+ Improved safety–

Lower voltage than other cathodes

–

Poor Li diffusion (DLi

~ 10-13

cm2/Sec)–

Poor electronic conductivity (~ 10-8

S/cm)

•

Approach many use to overcome poor characteristics—

Use nano

LiFePO4

–

carbon composite—

Use larger number of cells—

Nano

structured materials

Source: Various papers from the 23rd International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

Source: On line brochures from Valence Technology, http://www.valence.com/ucharge.asp

16

Improvements in Iron Phosphate Li-Ion Batteries

Valence Technology 18650 Cells100 Wh/kg in cell 84 Wh/kg in U Charge module

The battery with standard lead acid battery form factor includes a battery management system.

Source: On line brochures from Valence Technology, http://www.valence.com/ucharge.asp

Source: Andrew Chu (A123 Systems) from the 23rd International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

A123 Systems with 26650 Cells

100 Wh/kg

17

Improving Li-Ion Batteries with Titanate

Anode

Altaire

Nanotechnologies Inc.•

Improved low temperature performance

•

Faster charge acceptance•

Longer cycle life•

80-100 Wh/kg•

2000-4000 W/kg

Source: E. House (Altair Nanotechnologies) from the 23rd

International Battery Seminar & Exhibit, March 13-16, Ft. Lauderdale, FL.

18

PHEV Battery Options Need for higher energy than HEVs, so P/E lower

SAFT VLE 45

SAFT VLM 41

SAFT VLP 7

1

2

5

10

Avestor SE 48S63

SAFT VLM 27

SAFT VLP 20

SAFT VLP 30

Cyclon D

Cyclon E

Varta Li 60Ah

Varta Li 6Ah

Prius PEVE SAFT VLE module

SAFT VL41M module

SAFT VL30P module

Cobasys 1000

Cobasys 4500

Cobasys 9500

20501002005001000

SAPHION U1-12FN40SAPHION U24-12FN100

SAPHION U27-FN130

Optima D51

Optima D34

Optima D35

PEVE 7.5Ah

Kokam SLPB30205130

Kokam SLPB41205130Kokam SLPB55205130

Kokam SLPB78216216

Kokam SLPB100216216

Kokam SLPB60460330

Kokam SLPB80460330

SAFT NiMH 12

SAFT VHF 10SSAFT VHF 20S

SAFT VHF 30S

SAFT STM 5-100 MRSAFT STM 5-140 MR

Sprinter Varta

Varta Ni HP

Varta Ni UHP

Prius+ SAPHION

Sprinter SAFT

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 30 60 90 120 150

Available specific energy (Wh/kg)

Spec

ific

pow

er (W

/kg)

PHEVdesign space

Expanded

Source: Tony Markel and Andrew Simpson, Milestone Report, National Renewable Energy Laboratory, Golden, CO, September 2005.

P/E = Power/ Energy (W/Wh)

19

4000

50%

70%

Battery Cycle Life Depends on State of Charge Swing

•

PHEV battery likely to deep-cycle each day driven: 15 yrs equates to 4000-5000 deep cycles•

Also need to consider combination of high and low frequency cycling

Source: Christian Rosenkranz

(Johnson Controls) at EVS 20, Long Beach, CA, November 15-19, 2003

20

Summary: Exciting Times for Li-Ion Batteries

•

New Cathodes—

Lower cost—

Higher power—

Better safety—

Improved life•

New Anodes

—

Faster charge rate—

Improved life•

New Electrolyte

—

Improved safety—

Improved low temperature performance•

New Separator

—

Lower cost—

Improved safety

21

Battery Definition as Key Input to Simulation

kWh/mi(from simulation)

SOC window

PHEV range

P/E ratio

Performance constraints

kWh usable

kWh total

kWmotor

kWengine

DOH

Benefit of plugging-in

Benefit of hybridization

Total MPG Benefit

mass compounding

Input parameters

that define the battery

in BLUE

DOH = degree of hybridization

Source: Tony Markel and Andrew Simpson, Milestone Report, National Renewable Energy Laboratory, Golden, CO, September 2005.

22

-30

-20

-10

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40Distance (mi)

Pow

er (k

W)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

SOC

(%)

enginemotorSOC

Alternative PHEV Design Strategies: All-Electric vs

Blended

•

Engine turns on when battery reaches low state of charge•

Requires high power battery and motorAll-Electric (Pure EV or ZEV)

c h a r g e

Charge depleting(motor only) Charge sustaining

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

23

Alternative PHEV Design Strategies: All-Electric vs

Blended

•

Engine turns on when power exceeds battery power capability•

Engine only provides load that exceeds battery power capability

-30

-20

-10

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40Distance (mi)

Pow

er (k

W)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

SOC

(%)

enginemotorSOC

Blended

Charge depleting (motor + engine) Charge sustaining

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

24

0 10 20 30 40 50 600

0.1

0.2

0.3

0.4

Fuel

Con

sum

ptio

n

PHEV20 on LA92

0 10 20 30 40 50 600

20

40

60

80

100

Energy Storage System Rated Power (kW)

CD M

ode

Pet

role

umC

onsu

mpt

ion

Red

uctio

n (%

)

Electricity (kWh/mi)

Gasoline (L/mi)

Blended

All-E

lectric

Blended vs. AER Consumption Tradeoff

•

Reducing ESS power should reduce cost, mass, volume

•

50% reduction in power still provides almost all of the fuel consumption benefit

* CD = Charge DepletingP

ower Battery Limit

Battery

Engine

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

25

PHEV Battery Sizing Alternatives

0

10

20

30

40

50

60

0 5 10 15 20 25 30Energy (kWh)

Pow

er (k

W)

PHEV20 - BlendedPHEV20 - AERPHEV40 - BlendedPHEV40 - AER

50% SOC Window70% SOC Window

AER

Blended

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

26

Battery Cost Model based on P/E Ratio

0

200

400

600

800

1000

1200

0 5 10 15 20 25 30

Power-to-Energy (P/E) Ratio

Mod

ule

Cos

t ($/

kWh)

Near TermLong Term

Lower power to energy ratio

leads to lighter, smaller, and less expensive

energy storage system.

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

27

Battery SOC Operating Window vs. Specified All-Electric Range

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40 50 60

Daily Mileage / All-Electric Range

SOC widow

Daily mileage distribution

Battery Model (cont.) –

SOC Window

SOC operating window

Source: Andrew Simpson (NREL), Presented to FreedomCAR Vehicle System Analysis Team, March 1 2006

28

Real Driving Survey Data•

Provides valuable insight into travel behavior

•

GPS augmented surveys supply details needed for vehicle simulation

Source: Tony Markel, Presentation at Clean City Congress and Expo, (NREL), Phenoix, AZ, May 8, 2006

29

•

St. Louis data set includes 227 vehicles from 147 households•

Complete second by second driving profile for one day•

8650 miles of travel•

St. Louis data set is a small sample of real data •

NPTS data is generated from mileage estimates

St. Louis Travel Data Analysis Daily Driving Distance Similar to 1995 NPTS Data

0

2

4

6

8

10

12

0 0-55-1010

-15

15-20

20-2

525

-30

30-3

535

-40

40-45

45-50

50-55

55-6

060

-65

65-7

070-

7575

-80

80-8

585

-90

90-9

595

-100

Daily Distance (mi)Fr

eque

ncy

(%)

0

10

20

30

40

50

60

70

80

90

100

Cum

mul

ativ

e Fr

eque

ncy

(%)

1995 NPTS Data

~33 mi0

1

2

3

4

5

6

7

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98100

Daily Travel Distance (miles)

Freq

uenc

y (%

)

0

10

20

30

40

50

60

70

80

90

100

Cum

ulat

ive

Freq

uenc

y (%

)

Frequency (%)Cumulative Freq. (%)

~29 mi

St. Louis HHTS Data

Source: Tony Markel, Jeff Gondor, and Andrew Simpson (NREL), Presented to FreedomCAR Vehicle System Analysis Team, June 14 2006

30

0 5 10 15 20 25 300

5

10

15

20

25

30

35

40

Time of Day (hr)

Per

cen

tag

e o

f V

ehic

le F

leet

In U

se (

%)

0 5 10 15 20 25 300

50

100

150

200

250

300

350

400

Cu

mu

lati

ve F

uel

Co

nsu

med

(g

allo

ns)

ConventionalHybridPHEV20PHEV40

PHEVs

Reduce Fuel Consumption By >50% On Real-

World Driving Cycles

•

8647 total miles driven•

100% replacement of sample fleet

227 vehicles from St. Louis each modeled as a conventional, hybr227 vehicles from St. Louis each modeled as a conventional, hybrid and PHEVid and PHEV

26 mpg

58 mpg & 140 Wh/mi

PHEVs:>40% reduction in energy

costs>$500 annual savings

37 mpg

76 mpg & 211 Wh/mi

Assumes $2.41/gal and 9¢/kWh

$1.21

$1.58

$2.48

$3.45

Gas.

Average Daily Costs

$0.72

$0.48

---

---

Elec.

5.1

5.4

6.5

9.1

¢/mi

PHEV40

PHEV20

HEV

CV

Source: Tony Markel and Andrew Simpson (NREL), AABC-06, Baltimore, MD, May 19, 2006

31

Fuel Economy and All Electric Range Comparison

•

Difference between rated (EPA drive cycles) and Real median values are significant for the PHEVs

—

Consumers likely to observe fuel economy higher than rated value in typical driving

—

Vehicles designed with all electric range likely to operate in a blended mode to meet driver demands

** Fuel economy values do not include electrical energy consumption

Rated Median Rated MedianConventional 26 24.4 n/a n/aHEV 39.2 35.8 n/a n/aPHEV20 54 70.2 22.3 5.6PHEV40 67.4 133.6 35.8 3.8

Fuel Economy (mpg) ** All Electric Range (mi)

Source: Tony Markel, Jeff Gondor, and Andrew Simpson (NREL), Presented to FreedomCAR Vehicle System Analysis Team, June 14 2006

32

Concluding Remarks –

Vehicle Simulations

•

Simulations on sample real-world drive cycles suggests PHEV technology can dramatically reduce petroleum consumption.

•

Benefits of a PHEV over a conventional vehicle or HEV are tied to travel behavior.

•

A vehicle designed for all electric range in urban driving will likely provide only limited electric operation in real world applications

—

Still provides significant fuel displacement

•

Plug-in hybrid technology can reduce petroleum consumption beyond that of HEV technology.

33

Concluding Remarks -

Battery

•

Batteries with low power to energy ratios would be needed for PHEVs

•

Expansion of the energy storage system usable state of charge window while maintaining life will be critical for reducing system cost and volume

•

A blended operating strategy as opposed to an all electric range focused strategy may provide some benefit in reducing cost and volume while maintaining petroleum consumption benefits

•

The key remaining barriers to commercial PHEVs are battery life, packaging and cost.

34

Some Final Thoughts

•

PHEVs

reduce emissions and displace petroleum —

Is there a need to require ZEV (pure EV) range?

—

Does blended EV range achieve both objectives?•

Does AER or ZEV need to be over a “standard”

drive cycle or “real”

drive cycles?•

DOE and others are focusing R&D to reduce battery cost and to improve performance and life.

•

Incentives for PHEVs

with larger EV range (larger battery pack) may be needed.

•

Learning demonstrations are key in the short term –

a good role for AQMD.

35

Acknowledgments

•

DOE Program Support–

Dave Howell

–

Tien Duong

•

NREL Technical Support–

Tony Markel

–

Andrew Simpson–

Jeff Gonder